Metal housings are widely used for wireless communication devices, such as mobile phones or personal digital assistants (PDAs). Antennas are also important components in wireless communication devices for receiving and transmitting wireless signals at different frequencies, such as wireless signals operated in a long term evolution (LTE) band. However, when the antenna is located in the metal housing, the antenna signals are often shielded by the metal housing. This can degrade the operation of the wireless communication device.